As general antidiabetic agents having a hypoglycemic effect, insulin preparations and oral hypoglycemic agents are mainly utilized. The oral hypoglycemic agents may, for example, be islet-activating agents represented by sulfonylurea agents, liver gluconeogenesis inhibitors represented by biguanides and insulin sensitizers represented by thiazolidine derivatives. However, these therapeutic medicines are not effectively affect on many patients, and it is not easy to control the blood glucose level only by these therapeutic medicines, and various diabetic complications are caused in fact. Among peripheral organs in the body, a muscle is the most important tissue which plays a role of glucose metabolism at the time of hyperglycemia, and a decrease in glucose uptake activity of skeletal muscle cells is considered to be one of great factors causing hyperglycemia to diabetic patients. Therapeutic medicines for diabetes which directly accelerate glucose uptake activity in skeletal muscles as a principal action without depending on insulin are hypoglycemic agents of new types, and therapeutic medicines as disclosed in JP-A-6-345647 and JP-A-8-12579 have been proposed, but have not been used practically yet. These patent applications disclose that it takes so long time of 24 hours to apply a compound under test to skeletal muscle cells, and do not disclose the effect in a case of application for a level of 1 hour. The present inventors have found that a stimulating effect on glucose uptake is obtained by applying compounds of the formula (I) as described hereinafter having structures totally different from those in the above patent applications to skeletal muscle cells for a short time. Further, they have also confirmed that the compounds of the formula (I) as described hereinafter show a hypoglycemic effect or an effect of improving impaired glucose tolerance, several hours after administration of the compounds to diabetic KK-Ay mice and the like.
As compounds having chemical structures analogous to those of the compounds of the formula (I) as described hereinafter, compounds as disclosed in WO97/35550, WO99/60858 and WO00/44754 may be mentioned. However, these patent applications fail to disclose the effect as stimulators of glucose uptake in skeletal muscle cells.